diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 5cbc4bb1b395..df5e961484e1 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -105,8 +105,11 @@ static int scatter_elem_sz_prev = SG_SCATTER_SZ; static int sg_add(struct device *, struct class_interface *); static void sg_remove(struct device *, struct class_interface *); +static DEFINE_SPINLOCK(sg_open_exclusive_lock); + static DEFINE_IDR(sg_index_idr); -static DEFINE_RWLOCK(sg_index_lock); +static DEFINE_RWLOCK(sg_index_lock); /* Also used to lock + file descriptor list for device */ static struct class_interface sg_interface = { .add_dev = sg_add, @@ -143,7 +146,8 @@ typedef struct sg_request { /* SG_MAX_QUEUE requests outstanding per file */ } Sg_request; typedef struct sg_fd { /* holds the state of a file descriptor */ - struct list_head sfd_siblings; /* protected by sfd_lock of device */ + /* sfd_siblings is protected by sg_index_lock */ + struct list_head sfd_siblings; struct sg_device *parentdp; /* owning device */ wait_queue_head_t read_wait; /* queue read until command done */ rwlock_t rq_list_lock; /* protect access to list in req_arr */ @@ -166,12 +170,13 @@ typedef struct sg_fd { /* holds the state of a file descriptor */ typedef struct sg_device { /* holds the state of each scsi generic device */ struct scsi_device *device; + wait_queue_head_t o_excl_wait; /* queue open() when O_EXCL in use */ int sg_tablesize; /* adapter's max scatter-gather table size */ u32 index; /* device index number */ - spinlock_t sfd_lock; /* protect file descriptor list for device */ + /* sfds is protected by sg_index_lock */ struct list_head sfds; - struct rw_semaphore o_sem; /* exclude open should hold this rwsem */ volatile char detached; /* 0->attached, 1->detached pending removal */ + /* exclude protected by sg_open_exclusive_lock */ char exclude; /* opened for exclusive access */ char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */ struct gendisk *disk; @@ -220,14 +225,35 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd) return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE); } +static int get_exclude(Sg_device *sdp) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&sg_open_exclusive_lock, flags); + ret = sdp->exclude; + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags); + return ret; +} + +static int set_exclude(Sg_device *sdp, char val) +{ + unsigned long flags; + + spin_lock_irqsave(&sg_open_exclusive_lock, flags); + sdp->exclude = val; + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags); + return val; +} + static int sfds_list_empty(Sg_device *sdp) { unsigned long flags; int ret; - spin_lock_irqsave(&sdp->sfd_lock, flags); + read_lock_irqsave(&sg_index_lock, flags); ret = list_empty(&sdp->sfds); - spin_unlock_irqrestore(&sdp->sfd_lock, flags); + read_unlock_irqrestore(&sg_index_lock, flags); return ret; } @@ -239,6 +265,7 @@ sg_open(struct inode *inode, struct file *filp) struct request_queue *q; Sg_device *sdp; Sg_fd *sfp; + int res; int retval; nonseekable_open(inode, filp); @@ -267,52 +294,54 @@ sg_open(struct inode *inode, struct file *filp) goto error_out; } - if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE))) { - retval = -EPERM; /* Can't lock it with read only access */ + if (flags & O_EXCL) { + if (O_RDONLY == (flags & O_ACCMODE)) { + retval = -EPERM; /* Can't lock it with read only access */ + goto error_out; + } + if (!sfds_list_empty(sdp) && (flags & O_NONBLOCK)) { + retval = -EBUSY; + goto error_out; + } + res = wait_event_interruptible(sdp->o_excl_wait, + ((!sfds_list_empty(sdp) || get_exclude(sdp)) ? 0 : set_exclude(sdp, 1))); + if (res) { + retval = res; /* -ERESTARTSYS because signal hit process */ + goto error_out; + } + } else if (get_exclude(sdp)) { /* some other fd has an exclusive lock on dev */ + if (flags & O_NONBLOCK) { + retval = -EBUSY; + goto error_out; + } + res = wait_event_interruptible(sdp->o_excl_wait, !get_exclude(sdp)); + if (res) { + retval = res; /* -ERESTARTSYS because signal hit process */ + goto error_out; + } + } + if (sdp->detached) { + retval = -ENODEV; goto error_out; } - if (flags & O_NONBLOCK) { - if (flags & O_EXCL) { - if (!down_write_trylock(&sdp->o_sem)) { - retval = -EBUSY; - goto error_out; - } - } else { - if (!down_read_trylock(&sdp->o_sem)) { - retval = -EBUSY; - goto error_out; - } - } - } else { - if (flags & O_EXCL) - down_write(&sdp->o_sem); - else - down_read(&sdp->o_sem); - } - /* Since write lock is held, no need to check sfd_list */ - if (flags & O_EXCL) - sdp->exclude = 1; /* used by release lock */ - if (sfds_list_empty(sdp)) { /* no existing opens on this device */ sdp->sgdebug = 0; q = sdp->device->request_queue; sdp->sg_tablesize = queue_max_segments(q); } - sfp = sg_add_sfp(sdp, dev); - if (!IS_ERR(sfp)) + if ((sfp = sg_add_sfp(sdp, dev))) filp->private_data = sfp; - /* retval is already provably zero at this point because of the - * check after retval = scsi_autopm_get_device(sdp->device)) - */ else { - retval = PTR_ERR(sfp); - if (flags & O_EXCL) { - sdp->exclude = 0; /* undo if error */ - up_write(&sdp->o_sem); - } else - up_read(&sdp->o_sem); + set_exclude(sdp, 0); /* undo if error */ + wake_up_interruptible(&sdp->o_excl_wait); + } + retval = -ENOMEM; + goto error_out; + } + retval = 0; error_out: + if (retval) { scsi_autopm_put_device(sdp->device); sdp_put: scsi_device_put(sdp->device); @@ -329,18 +358,13 @@ sg_release(struct inode *inode, struct file *filp) { Sg_device *sdp; Sg_fd *sfp; - int excl; if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp))) return -ENXIO; SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name)); - excl = sdp->exclude; - sdp->exclude = 0; - if (excl) - up_write(&sdp->o_sem); - else - up_read(&sdp->o_sem); + set_exclude(sdp, 0); + wake_up_interruptible(&sdp->o_excl_wait); scsi_autopm_put_device(sdp->device); kref_put(&sfp->f_ref, sg_remove_sfp); @@ -1391,9 +1415,8 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp) disk->first_minor = k; sdp->disk = disk; sdp->device = scsidp; - spin_lock_init(&sdp->sfd_lock); INIT_LIST_HEAD(&sdp->sfds); - init_rwsem(&sdp->o_sem); + init_waitqueue_head(&sdp->o_excl_wait); sdp->sg_tablesize = queue_max_segments(q); sdp->index = k; kref_init(&sdp->d_ref); @@ -1526,13 +1549,11 @@ static void sg_remove(struct device *cl_dev, struct class_interface *cl_intf) /* Need a write lock to set sdp->detached. */ write_lock_irqsave(&sg_index_lock, iflags); - spin_lock(&sdp->sfd_lock); sdp->detached = 1; list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) { wake_up_interruptible(&sfp->read_wait); kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP); } - spin_unlock(&sdp->sfd_lock); write_unlock_irqrestore(&sg_index_lock, iflags); sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic"); @@ -2043,7 +2064,7 @@ sg_add_sfp(Sg_device * sdp, int dev) sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN); if (!sfp) - return ERR_PTR(-ENOMEM); + return NULL; init_waitqueue_head(&sfp->read_wait); rwlock_init(&sfp->rq_list_lock); @@ -2057,13 +2078,9 @@ sg_add_sfp(Sg_device * sdp, int dev) sfp->cmd_q = SG_DEF_COMMAND_Q; sfp->keep_orphan = SG_DEF_KEEP_ORPHAN; sfp->parentdp = sdp; - spin_lock_irqsave(&sdp->sfd_lock, iflags); - if (sdp->detached) { - spin_unlock_irqrestore(&sdp->sfd_lock, iflags); - return ERR_PTR(-ENODEV); - } + write_lock_irqsave(&sg_index_lock, iflags); list_add_tail(&sfp->sfd_siblings, &sdp->sfds); - spin_unlock_irqrestore(&sdp->sfd_lock, iflags); + write_unlock_irqrestore(&sg_index_lock, iflags); SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp)); if (unlikely(sg_big_buff != def_reserved_size)) sg_big_buff = def_reserved_size; @@ -2113,9 +2130,10 @@ static void sg_remove_sfp(struct kref *kref) struct sg_device *sdp = sfp->parentdp; unsigned long iflags; - spin_lock_irqsave(&sdp->sfd_lock, iflags); + write_lock_irqsave(&sg_index_lock, iflags); list_del(&sfp->sfd_siblings); - spin_unlock_irqrestore(&sdp->sfd_lock, iflags); + write_unlock_irqrestore(&sg_index_lock, iflags); + wake_up_interruptible(&sdp->o_excl_wait); INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext); schedule_work(&sfp->ew.work); @@ -2502,7 +2520,7 @@ static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v) return 0; } -/* must be called while holding sg_index_lock and sfd_lock */ +/* must be called while holding sg_index_lock */ static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp) { int k, m, new_interface, blen, usg; @@ -2587,26 +2605,22 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v) read_lock_irqsave(&sg_index_lock, iflags); sdp = it ? sg_lookup_dev(it->index) : NULL; - if (sdp) { - spin_lock(&sdp->sfd_lock); - if (!list_empty(&sdp->sfds)) { - struct scsi_device *scsidp = sdp->device; + if (sdp && !list_empty(&sdp->sfds)) { + struct scsi_device *scsidp = sdp->device; - seq_printf(s, " >>> device=%s ", sdp->disk->disk_name); - if (sdp->detached) - seq_printf(s, "detached pending close "); - else - seq_printf - (s, "scsi%d chan=%d id=%d lun=%d em=%d", - scsidp->host->host_no, - scsidp->channel, scsidp->id, - scsidp->lun, - scsidp->host->hostt->emulated); - seq_printf(s, " sg_tablesize=%d excl=%d\n", - sdp->sg_tablesize, sdp->exclude); - sg_proc_debug_helper(s, sdp); - } - spin_unlock(&sdp->sfd_lock); + seq_printf(s, " >>> device=%s ", sdp->disk->disk_name); + if (sdp->detached) + seq_printf(s, "detached pending close "); + else + seq_printf + (s, "scsi%d chan=%d id=%d lun=%d em=%d", + scsidp->host->host_no, + scsidp->channel, scsidp->id, + scsidp->lun, + scsidp->host->hostt->emulated); + seq_printf(s, " sg_tablesize=%d excl=%d\n", + sdp->sg_tablesize, get_exclude(sdp)); + sg_proc_debug_helper(s, sdp); } read_unlock_irqrestore(&sg_index_lock, iflags); return 0;